Abstract:

The biology and behavior of the codling moth, Cydia pomonella (L.), was studied to
determine factors responsible for differences in susceptibility to moth damage among apple
and pear cultivars.
In release experiments, codling moth adults were intercepted in significantly greater
numbers in host (apple, pear) than in non-host (maple) trees, suggesting a directed response
rather than random movement to host trees. There was no correlation between adult
preference for certain hosts and the susceptibility of the hosts to codling moth attack. Adults
were guided by cues from the tree canopy, foliage and fruit. Cues from host fruit were less
important at the beginning of the season. Similar adult behavior patterns were observed in
different coding moth strains. However, moths reared on apples were guided more by
olfactory cues from fruit than sterilized moths reared on artificial diet.
The percentage of moths mating under caged conditions was higher in apple and
pear than in maple trees. In host plants, stimuli from fruit were not essential for mating.
The egg distribution in the field varied through the season depending on the host cultivar.
However, mean distance of eggs to fruit, as well as larval travel speed, was not different
among host cultivars. Selection of an oviposition site by the adult female was affected by
several factors, including visual, chemical, and tactile stimuli of host fruit, as well as
anatomical (pubescence) and chemical (oviposition stimulants) properties of leaves.
There were no differences in natural mortality and developmental rates of the egg
stage on host cultivars. However, there were significant differences in first instar larval
mortality among hosts over most of the season. Mortality was much higher on 'Anjou' than
on 'Bartlett' and 'Red Delicious', except at the end of the season. Differential first instar
mortality was due to the different rate of success in entering the fruit. The ability to
penetrate fruit was correlated with infestation levels observed in the field and related both to
neonate behavior and anatomical characteristics of host fruits.
Larval food source did not affect larval and pupal development rates, adult
fecundity, or egg viability.